         sigma (/ mean 6)]
     (tuc/draw-normal mean sigma)))
 
-(defn convert-units-f [from to]
-  (let [factors {[:m :ft] 3.28084
-                 [:kg :lb] 2.20462262185
-                 [:m3 :bbl] 6.28981077
-                 [:psi :kPa] 6.894757293168361
-                 [:M :k] 1000}
-        converter {[:ft :m] #(/ % (factors [:m :ft]))
-                   [:m :ft] #(* % (factors [:m :ft]))
-                   [:lb :kg] #(/ % (factors [:kg :lb]))
-                   [:kg :lb] #(* % (factors [:kg :lb]))
-                   [:bbl :m3] #(/ % (factors [:m3 :bbl]))
-                   [:m3 :bbl] #(* % (factors [:m3 :bbl]))
-                   [:psi :kPa] #(* % (factors [:psi :kPa]))
-                   [:kPa :psi] #(/ % (factors [:psi :kPa]))
-                   [:kPa :MPa] #(/ % (factors [:M :k]))
-                   [:MPa :kPa] #(* % (factors [:M :k]))
-                   [:C :F] #(+ (* % 1.8) 32)}]
-    (converter [from to])))
-
 (def physical-quantities [:length :mass :pressure :volume :injection-rate :proppant-concentration])
 
 (defn rand-physical-quantity []

  #?(:cljs (:require [test-utils.core :as tuc])
     :clj (:require (test-utils [core :as tuc]))))

(defn typical-vertical-depth []
  (tuc/draw-normal 8000 1216))


(defn typical-stage-top []
  (tuc/draw-normal 13750 2150))

(defn typical-stage-length
  ([] (let [length-unit (rand-nth [:ft :m])]
        [length-unit (typical-stage-length length-unit)]))
  ([length-unit]
   (condp = length-unit
     :ft [:ft (tuc/draw-normal 152 17)]
     :m [:m ((convert-units-f :ft :m) (nth (typical-stage-length :ft)))])))

(defn typical-stage-extent
  ([]
